I've got a couple of those Californina Wonder gas cans, I know for a fact that they will emit both fumes and liquid, even if only filled to 4.5 gals in a 5 gal can. Plus, those wonderful no-spill spouts that come with them usually end up spilling more gas than a reqular old flex spout. Once again CA has tried to solve a non-existant problem with an over engineered piece of junk...